Most windows in airplane cabins are configured with window shades constructed of a single solid, thin panel. Shades configured in escape hatch doors often use window shades that are flexible and affixed with rollers about which the flexible window shade rolls up because such hatches have too little space to allow a solid shade to function. Where there is space available, solid shades have proven to provide better performance and longevity than roller shades, primarily due to their simplicity as solid shades do not require roller mechanisms and related devices. Although solid shades use shade tracks on both sides of the shade that are similar to shade tracks used in roller shade systems, a solid shade and its handle are molded together into a single solid body structure. When a solid shade is traveling (i.e., sliding up or down) in the tracks, the left and right edges of the handle of the solid shade and the left and right edges of the shade itself function as a shade guide, attempting to maintain a perpendicular geometry with tracks. In a roller shade system, the shade itself is a flexible material (e.g., cloth) with the handle being solid and performing the shade guide function. In such systems, the shade handle is responsible for maintaining perpendicularity to the left and right shade tracks, as shown in FIG. 1A.
In solid shade systems, but not usually in roller shade systems, a handle and shade may help maintain the shade in a perpendicular position relative to the shade tracks as the shade itself also functions as a shade guide. When the handle is not perpendicular to the tracks or the ends of the handle are otherwise are out of alignment with each other, the handle may twist as shown in FIG. 1B. This twisting may result in the handle becoming stuck or inhibited from travel within the tracks, thereby preventing easy operation of the shade. Handle twisting may also cause shade damage, such as wrinkling in the shade as shown in FIG. 2. This wrinkling may be aesthetically unpleasant for passengers. Handle twisting may further lead to more severe damage, such as a shade and handle escaping their intended geometry as shown in FIG. 3.
Wrinkling of a shade can also occur due to changes in temperature and moisture at the shade. The exterior of an aircraft, and components inside an aircraft but proximate to the exterior, such as a shade, can experience extreme temperature and moisture variations and ultraviolet light exposure during normal operation of the aircraft. The material from which shades are constructed expands and contracts due to these temperature and moisture variations, which can result in wrinkling as shown in FIG. 4.
In any of these situations, even if the wrinkles in a shade are straightened out periodically, after a period of time wrinkles introduced into a shade will eventually fatigue and cause the material to permanently show the wrinkles (i.e., “shade memory”), giving the shade an unacceptable appearance and potentially causing other damage.